/* This program calcutates pi using a monte carlo simulation
 *
 * Mark Monarch
 * 2/25/15
 */
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <time.h>

using namespace std;

int main()
{
    // prepares random number generator
    srand(time(NULL));

    // declare variables
    float   x,
            y,
            piEstimate;
    long    trials,
            inCircle = 0;

    // asks user for number of trials. The more trials, the more accurate it will be
    cout << "Input number of trials: ";
    cin >> trials;

    // runs the trials
    for (int i = 0; i < trials; i++)
    {
        // randomly gets x value
        x = (float)(rand() % 9999) / 9999.0;
        // randomly gets y value
        y = (float)(rand() % 9999) / 9999.0;
        if (x*x+y*y < 1) // if point is in the circle
        {
            inCircle++;
        }
    }

    // finds the ratios between the areas
    piEstimate = 4.0 * (float) inCircle / (float) trials;

    // display pi estimate
    cout << endl << "Pi is approximately: " << piEstimate << endl;

    // Waits for user
    system("PAUSE");

    // return
    return 0;
}